EXFO FastReporter 2 - Manual (Page 67)

Working with Projects (FR2-FC Mode)
Post Processing Software 57
Working in Loopback Mode
Working in Loopback Mode
The loopback mode allows you to test both A -> B and B -> A, and
Tx and Rx at once, which saves time and manipulations. You can set the
loop length yourself, or let the application find it automatically with a
default loop length.
This mode is available for both OTDR and iOLM measurement files.
If you have activated the loopback option for your application, it is ready to
use when needed. You can use the loopback mode that fits your needs:

Unidirectional: Will split the measurement file into two directions, with
the corresponding verdict.

Bidirectional: Will split two unidirectional files set as a virtual
bidirectional file each their two directions.
Note: Files created using the loopback mode cannot be used again to perform a
bidirectional loopback, but you can redo a loopback with the unidirectional
mode result files.
Note: You cannot perform bidirectional loopback tests on multimode files.